Deb's Metabolic Efficiency Test

One of the most enjoyable things I like to do is help my clients meet their goals. I understand the importance of this since I too had felt that passion and desire to do my best when I was a serious athlete.  Having the right equipment.  Having a successful training program. Having a race strategy. And having a nutrition plan to compliment my training and racing.

Back in my day of training and racing a nutrition plan revolved around carbs (CHO) as the main source of energy. And that does still hold true for most events that are short in duration that require high intensity efforts.  But not necessarily the case for longer distance events such as ultra running and iron distance triathlons. The longer distance athletes that relied on CHO found out that consuming too many of these CHOs would give them G.I. distress and if they taken in too little they would run out of energy.  

There is a great deal of research about energy demands at various levels of intensity. As well, there are studies of athletes that are labelled "Sugar Burners" or "Fat Burners."  Basically a Sugar Burner is using a great deal of CHO at lower intensity levels. Such as at Zone 1 or Zone 2 heart rate levels. On the otherhand, Fat Burners are burning more body fat (white fat) for energy at sub-threshold and higher zones such as upper Z4 and Z5, etc.

My goal in this post is not to go into Sugar and Fat Burners.  I will post about this topic in the near future. If you need to know more about this topic, check out my velo smart website.

My intent for this post is to talk about my friend and client Deb Elliott. Deb had a VO2/Metabolic Efficiency test yesterday (March 14th, 2017). Her goal was to find out her pacing and nutrition stragey for an Ironman competition later in the year.

So, before I conducted the test I asked her what her desired pacing strategies were and mostly wanted to know what her desired bike speed goal and her heart rate at the desired speed.

As you can see from the above group selfie and picture of Deb, she performed the MET Test on her bike. This was a good idea since a majority of an IM athlete's time at this type of race is on the bike.  It is also a good idea to know how many calories (both CHO and fat) will be used to come up with a nutrition and pacing plan to ensure Deb stays away from running out of energy or getting G.I. problems while running the marathon portion of her IM.

Once I had Deb set up on the bike, I placed a testing mask and hose that captures and measures the amount of O2 and CO2 during her exhalations.  As you can guess, the lower her work load the more O2 would be exhaled. But at higher intensities she would begin exhaling more CO2. So what does this mean?  Well basically (let's not bore you with all the science), CO2 is a by product of lactic acid.  Lactic acid is a by product of CHO. There is actually more going on here but athlete's just want to know how to go faster and longer. Enough said.

After placing the mask and hose to Deb that is connected to my metabolic cart she began her test.  She was pedalling at a steady pace and she was instructed to maintain this pace throughout the duration of the test. Easy right? Well, sure it was easy at the beginning at only 50 watts resistance. However, every 60 seconds I increased the resistance. As the resistance was being increase, her heart rate would rise and more CO2 would be exhaled from her lungs.  So with this process I was able to identify her hear rate zones, her total calories per hour at these zones, and total of CHO and fat calories at these heart rate levels.  For this blog post I am only providing Deb's energy demands at various heart rate levels.  As you can see as I increased the resistance, Deb's heart rate would go up. As her heart rate inclined should begin to rely on more CHO for energy.

This source of information is very helpful for Deb.  For example let's say her goal pace on the bike is 18 mph. And at 18 mph her heart rate is 135 bpm what does the data provide?  Well based on this data, she can extrapulate that she is using 350 CHO calories per hour.  Now she can determine how much she needs to eat while on the bike to keep from running out of energy or if consuming this many calories could cause G.I.

Another piece of information that can be gained from this test is creating a plan to become less CHO reliant (if warranted) and more fat efficient. To do so, I can recommend a nutrition and training plan for her to burn more fat calories at higher intensity levels.  But this will be in a future blog post.

Yours in Cycling and Fitness,
Greg Combs
President of Fun
​May Street Bicycles is not your typical bike shop. Sure we sell awesome bicycles, provide bicycle repairs, and rental bikes all at great prices. But we do a great deal more such as dynamic bike fitting, metabolic testing, altitude training, and personal training.